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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 11 Aug 2021 10:03:49 +0300
Message-ID: <CAHp75VfaeEzodmPPmxxDoScPQzE2+5D_czEHfF0pq6oOVh-6nw@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] iio: potentiometer: Add driver support for AD5110
To:     Mugilraj Dhavachelvan <dmugil2000@gmail.com>
Cc:     "Bogdan, Dragos" <Dragos.Bogdan@analog.com>,
        Darius <Darius.Berghe@analog.com>,
        Rob Herring <robh+dt@kernel.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Chris Packham <chris.packham@alliedtelesis.co.nz>,
        Slawomir Stepien <sst@poczta.fm>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-iio <linux-iio@vger.kernel.org>
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On Wed, Aug 11, 2021 at 8:46 AM Mugilraj Dhavachelvan
<dmugil2000@gmail.com> wrote:
> On Tue, Aug 10, 2021 at 03:49:52PM +0300, Andy Shevchenko wrote:
> > On Mon, Aug 9, 2021 at 10:59 AM Mugilraj Dhavachelvan
> > <dmugil2000@gmail.com> wrote:

...

> > > +       data->tol =3D data->cfg->kohms * (val & GENMASK(6, 0)) * 10 /=
 8;
> > > +       if (!(val & BIT(7)))
> > > +               data->tol *=3D -1;
> >
> > Shouldn't you simple use corresponding sign_extend*()?
> >
> I'm not able see any sign_extend for 16 bit. Is there any other way?

So, then add it in bitops.h the same way it's done for s32 and s64.

...

> > > +       if (!data->cfg)
> > > +               data->cfg =3D &ad5110_cfg[i2c_match_id(ad5110_id, cli=
ent)->driver_data];
> >
> > Not sure this is not a dead code since you are using ->probe_new().
> >
> Even I'm suspecting that and also removing id_table. But I'm not sure of
> it so just left as it is.

I=C2=B2C ID table is good to have without direct use, but ->probe_new() is
called if and only if there is a compatible string or ACPI ID match.
In such case data->cfg may be NULL if and only if the corresponding
table missed it, but this will be a bug anyway, so the above code will
rather hide the bug. Hence, please remove it.


--=20
With Best Regards,
Andy Shevchenko